Enhanced host–guest electrochemical recognition of herbicide MCPA using a β-cyclodextrin carbon nanotube sensor

Abstract

a b s t r a c tAn electrochemical sensor for the determination of the chlorophenoxy herbicide MCPA has been developed, based on a combination of multi-walled carbon nanotubes with incorporated b-cyclodextrin and a polyaniline film modified glassy carbon electrode. The proposed molecular host-guest recognition based sensor has a high electrochemical sensitivity for the determination of MCPA. The electrochemical behaviour of MCPA at the chemically modified electrode was investigated in detail by cyclic voltammetry. The results indicate that the b-CD/MWCNT modified glassy carbon electrode exhibits efficient electrocatalytic oxidation of MCPA with high sensitivity, stability and lifetime. The analytical characteristics of this film were used for the quantitative determination of MCPA in natural waters. Cyclic voltammetry in phosphate buffer solution at pH 6.0, allowed the development of a method to determine MCPA, without any previous steps of extraction, clean-up, or derivatization, in the range of 10-100 mmol L À 1 , with a detection limit of 0.99 mmol L À 1 in water. The results were statistically compared with those obtained through an established high-performance liquid chromatography technique, no significant differences having been found between the two methods.

Electrochemical Determination of the Herbicide Bentazone Using a Carbon Nanotube β‐Cyclodextrin Modified Electrode

“…MWCNT-modified electrodes incorporating b-cyclodextrin (b-CD) were prepared and characterized according to a previously reported procedure [24]. Briefly, a mass of 120 mg of MWCNT was stirred in 10 mL of a 5 mol L À1 nitric acid solution for 20 h. The solid product was collected on a filter paper and washed several times with double-distilled water until the filtrate solution became neutral (pH % 7).…”

“…deprotonated bentazone. Such a behavior can be explained considering that the negatively charged ÀCOO À groups existing at the ends or at the sidewall defects of the nanotube structure of functionalized carbon nanotubes [24] repel the bentazone anions, thereby reducing their access to the fMWCNT surface. A similar tendency was reported for the adsorption and electrosorption of bentazone on activated carbon cloth in aqueous solutions [29].…”

“…This structure leads to the formation of inclusion complexes with a variety of guest molecules that fit inside the torus-shaped cavities, which serve as host sites. Electrodes modified with multiwalled CNT (MWCNT) in which b-CD are incorporated have recently been successfully used to study and quantify many organic molecules owing to the excellent properties of both materials [22][23][24].…”

An Overview of Pesticide Monitoring at Environmental Samples Using Carbon Nanotubes-Based Electrochemical Sensors

“…A sequence of papers was reported by Rahemi et al [79,88,89] dedicated to the construction of pesticide electrochemical sensors based on β-cyclodextrin and carbon nanotubes. Cyclodextrin molecules are cyclic oligosaccharides formed of six to twelve α-D-glucopyranose monomers, which are linked by 1 and 4 carbon atoms [106].…”

“…Cyclodextrin molecules are cyclic oligosaccharides formed of six to twelve α-D-glucopyranose monomers, which are linked by 1 and 4 carbon atoms [106]. β-cyclodextrin (β-CD) is a type of cyclodextrin molecule constituted of seven D-glucopyranose units, which possesses a hydrophilic exterior and an interior hydrophobic cavity [89]. Cyclodextrin can be explored for electroanalytical proposes using its ability for molecular recognition and selective pre-concentration of analytes on the modified electrode surface [107][108][109].…”